Direct measurement of NO3 reactivity in a boreal forest

Measurement report: Photochemical production and loss rates of formaldehyde and ozone across Europe

Various atmospheric sources and sinks regulate the abundance of tropospheric formaldehyde (HCHO), which is an important trace gas impacting the HOx (≡ HO2 + OH) budget and the concentration of ozone (O3). In this study, we present the formation and destruction terms of ambient HCHO and O3 calculated from in situ observations of various atmospheric trace gases measured at three different sites across Europe during summertime. These include a coastal site in Cyprus, in the scope of the Cyprus Photochemistry Experiment (CYPHEX) in 2014, a mountain site in southern Germany, as part of the Hohenpeißenberg Photochemistry Experiment (HOPE) in 2012, and a forested site in Finland, where measurement…

Direct measurement of NO<sub>3</sub> reactivity in a boreal forest

Abstract. We present the first direct measurements of NO3 reactivity (or inverse lifetime, s−1) in the Finnish boreal forest. The data were obtained during the IBAIRN campaign (Influence of Biosphere-Atmosphere Interactions on the Reactive Nitrogen budget) which took place in Hyytiälä, Finland during the summer/autumn transition in September 2016. The NO3 reactivity was generally very high with a maximum value of 0.94 s−1 and displayed a strong diel variation with a campaign-averaged nighttime mean value of 0.11 s−1 compared to a daytime value of 0.04 s−1. The highest nighttime NO3-reactivity was accompanied by major depletion of canopy level ozone and was associated with strong temperature…

Direct measurement of NO<sub>3</sub> radical reactivity in a boreal forest

Abstract. We present the first direct measurements of NO3 reactivity (or inverse lifetime, s−1) in the Finnish boreal forest. The data were obtained during the IBAIRN campaign (Influence of Biosphere-Atmosphere Interactions on the Reactive Nitrogen budget) which took place in Hyytiälä, Finland during the summer/autumn transition in September 2016. The NO3 reactivity was generally very high with a maximum value of 0.94 s−1 and displayed a strong diel variation with a campaign-averaged nighttime mean value of 0.11 s−1 compared to a daytime value of 0.04 s−1. The highest nighttime NO3 reactivity was accompanied by major depletion of canopy level ozone and was associated with strong temperature…

Direct measurement of NO3 radical reactivity in a boreal forest

We present the first direct measurements of NO3 reactivity (or inverse lifetime, s−1) in the Finnish boreal forest. The data were obtained during the IBAIRN campaign (Influence of Biosphere-Atmosphere Interactions on the Reactive Nitrogen budget) which took place in Hyytiälä, Finland during the summer/autumn transition in September 2016. The NO3 reactivity was generally very high with a maximum value of 0.94 s−1 and displayed a strong diel variation with a campaign-averaged nighttime mean value of 0.11 s−1 compared to a daytime value of 0.04 s−1. The highest nighttime NO3 reactivity was accompanied by major depletion of canopy level ozone and was associated with strong temperature inversion…

Daytime formation of nitrous acid at a coastal remote site in Cyprus indicating a common ground source of atmospheric HONO and NO

Abstract. Characterization of daytime sources of nitrous acid (HONO) is crucial to understand atmospheric oxidation and radical cycling in the planetary boundary layer. HONO and numerous other atmospheric trace constituents were measured on the Mediterranean island of Cyprus during the CYPHEX campaign (CYPHEX = CYprus PHotochemical EXperiment) in summer 2014. Average volume mixing ratios of HONO were 35 pptv (±25 pptv) with a HONO/NOx ratio of 0.33, which was considerably higher than reported for most other rural and urban regions. Diel profiles of HONO showed peak values in the late morning (60±28 pptv around 09:00 local time), and persistently high mixing ratios during daytime (45±18 pptv…